Allisartan isoproxil (CAS: 947331-05-7) with the chemical name of 2-butyl-4-chloro-1-[2′-(1H-tetrazol-5-yl)-1,1′-biphenyl-methyl]-imidazole-5-carboxylic acid, 1-[(isopropoxy)-carbonyloxy]methyl ester, is a novel angiotensin II receptor antagonist. Chinese patent CN200680000397.8 disclosed the structural of allisartan isoproxil. Allisartan isoproxil shows low toxicity and superior antihypertensive efficacy compared with like products (e.g., losartan). Allisartan isoproxil exerts its antihypertensive effect by generating active metabolite (EXP3174).

According to the prior art, allisartan isoproxil shows poor flowability, small bulk density, and obvious electrostatic phenomenon. Chinese patent CN200710094131.0 disclosed an allisartan isoproxil crystal form and preparation method thereof. The allisartan isoproxil crystal prepared with this method shows high stability, but relatively small bulk density, poor flowability, and obvious electrostatic phenomenon after drying. It causes dust pollution during the pulverizing, sub-packaging and using of this crystal, which on the one hand causes inconvenience for cleaning and labor protecting in operation site, and on the other hand causes inconvenience for weighing accuracy and packaging.
Chinese patents CN200710094021.4 and CN201110289695.6 both disclosed the preparation methods of allisartan isoproxil, and as repeated by the inventor, the resulted crystal forms are consistent with that disclosed in CN200710094131.0.
In view of the aforementioned disadvantages of allisartan isoproxil disclosed in the prior art, it can be seen that the technical problem to be addressed firstly in the present invention is to obtain allisartan isoproxil with flowability suits for subsequent producing, with appropriate bulk density and without obvious electrostatic phenomenon.